Thermal relay



' june 11,1930. E. M. CLAYTOR 1 765, 05

' THERMAL RELAY Filed June 24, 1927 2 Sheets-Sheet 1 Fly. 2.

, INVENTOR fdn a/"d/ lC/ayfolr A'TTORNEY June 17,1930. E. M. CLAYTOR 1,755,305

THERMAL RELAY Filed June 24, 1927 2 Sheets-Sheet 2 5e H J 6/ 0a 75 INVENTOR Edward M C/ay lb/r ATTC')RNEY* EDWARD M. cLAYTeR, on winninsnuzee, J p

- HOUSE ELEoTRIc & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA latentecl June 17, 1 930 nnlrsoisrarss PATENT OFFICE PENNSYLVANIA, ASSIG-NOB T WESTING- THERMAL RELAY Application filed June 24, 1927. Serial No. 201,055.

- My invention relates to protective devices and particularly to thermal relays.

-- An object of my invention is to provide a relay thatshall be simple in construction and easily manufactured.

Another object of my invention is to provide a thermal relay that shall depend tor -its-operation nponthe change of magnetic properties in its thermal element.

A further object of my invention is to provide a thermal relay that shall be re-set auto- ---.matically.

- And a furtherobject of my invention is to provide automatic re-setting means for a thermal relay that shall be operable to permit the relay to operate only when a circuit-controlling device associated therewith is in a pre- 1 determined circuit-controlling position.

In practicing my invention, a circuit-controllin device, or an electric switch, 1S provided ror controlling such energy-translating devices as electric motors, etc.

In order that the-translating devices may be protected against overloads, athermal relay is pro-- vided for causing the switch to be actuated to a circuit-breaking position upon the occur nience of an overload of predetermined value.

"Means are provided also for re-setting the relay the 'moment the switch has been ac- The resetting means cooperates with the switch insuch manner that the relay is free to 'drop out'whenever the condition the thermal element is of a predetermined value, provided the switch is in a closed or ciij'cuitmaking position. For a fuller understanding of inven-. tion reference ma be had to the followin A description, taken in conjunction with the accompanying drawings, in which Figure 1 is a View, in side elevation, of a circuit-controlling device embodying my invention and Fig. 2 is a View, in front elevation, of the same device. I

Fig. 3 is a View, in section, taken on line HIIII of the device illustrated in Fig 1 and Fig. 4; is a schematic illustration of circuits and apparatus embodying my invention.

In the drawings, a panel or base 10 of insulating material is illustrated on which is mounted a stationary terminal 11. At the outer end of the terminal 11 is secured a con tact tip 12, of substantially L-shape', by means of a bolt 13. The contact tip 12 constitutes the stationary member or'contact of a main circuit interrupter. V

Beneath the terminal 11, a core frame ie is located and is secured to the panel 10 by means of a bolt 15 passing through the panel 10 and terminating in the core frame 14 with which it has screw-thread engagement. The frame 14 may be made of iron or'other suitable magnetic- 1naterial,-and, as illustrated, is in the form of abracket of substantially L-shape. The portion ofthe frame 1% eX- tending laterally from the panel 10 is provided with a'pair 0t spaced-apart portions 16 and 17 between which an armature 1.8 is located. The armature 18 may be made of iron orother suitablemagnetic material, and may be secured to the frame 14 by a hinge pinl9 that passes through the frame and the armature The hinge pin is provided, at opposite ends, with springclips 21 which prevent the same from sliding out of position, as will be readily understood by referringto Fig. 2 of the drawing.

The upper end of-the armature 18 is provided with spaced-apart lugs 22 between which a =movable'contact support 23 is located, the support 23 being hinged thereon by a hinge bolt 24 thatpasses through the lugs and the support. A contact tip 25 is secured to the outer end of the support 23 by shoulder portion 28 of the armature.

coil 39 is a bolt 26. The tip may be of substantially L-shape and similar in construction to the tip 12.

The adjacent faces of the tips 12 and 25 may be slightly circular in order that a rolling contact may be effected therebetween when the contacts are actuated into and out of engagement with each other.

In order that rolling'contact between adjacent faces of the tips 12 and 25 may be effected, a spring 27 is located between the lower face of the contact support'23 M19121 1e spring may be maintained in this position by lugs 29 and 30 that extend into the ends of the spring 27, the lugs being secured to, or made integral with, the movable support 23 and the armature 18, respectively.

So that the distance between contact tips 12 and 25 may be adjusted to any desired value, when the contacts are in a disengaged position, a tail piece 32 is provided as an integral part of the armature 18 at the end of which is mounted an adjusting screw 33. When the armature swings outwardly on the hinge pin 19, the upper end of the adjusting screw 33 engages the frame 14, thus limiting the turning movement of the armature 18 on the hinge pin.

In order that the armature 18 may be free from current-carrying duty, a shunt 35 is provided.- As shown, the ends of the shunt may be secured in a clip 36 attached to one of the lugs 22 and a clip'37 that is secured to the armaturenear the-panel 10. Thus, it is seen that, when the contact tips 12 and 25 are in the positions shown in Fig. 1, a.

circuit is completed from the terminal support 11 through the contact tips and the shunt 35 to the bolt 15.

The armature 18 may be actuated to the position shown in Fig. 1 and held in this position by means of a magnet coil 39. As shown, .the coil is held against the portion of the core frame 14 adjacent to the panel 10 by means of a plate 41 that is secured to a In 42 on the armature frame by a screw 43. he

rovided with a core 44 that passes through the coil, the outer end of which engages the up er end of armature 18 and the inner end 0 which rests against the core frame 14. The core may be secured in this position by a bolt 45 that extends through the panel and into the tapped end of the core with which it has screw-thread engagement.

The coil 39 is provided with terminals 46 and 47 which may be connected to a suitable source of electrical energy.

Whenthe coil 39 is energized, the armature 18 is actuated to the osition shown in the drawings. However,i the coil is de-energized, the armature swings outwardly to effect disengagement between the contact tips 12 and 25, In order to accelerate the outward movement of the armature, a ring 48 is provided that presses against the ower end of the plate 41 and the outer edge of the armature 18.

When the circuit interrupter, constituted by the contact tips 12 and 25, is in the position shown in the drawings, and the magnet coil is energized, a permanent energizing circuit may be established through the coil by means of an interlock 49. The interlock 49 comprises a bell-crank lever 51 that is pivotally mounted on a bracket 52. As shown, the upper end of the bell-crank lever 51 engages a bar 53 secured to the tail piece 32. The lower end of the bell-crank lever has a contact bridging member 54 secured thereto to bridge a pair of stationary contacts 55, which are included in the circuit of the magnet coil.

In order that the bell-crank lever 51 may swing to such 2 position that the bridging member 54 shall be disenga ed from the stationary contacts 55 when t e armature contact 18 is in a position to cause disengagement between contact tips 12 and 25, a spring 56 is provided and, as shown, is located between the bracket 52 and the lower portion of the bell crank lever 51. i

In order that the coil 39 may be de-energized to effect a release of the armature 18 to the position in which the switch contacts controlled thereby are actuated to a circuitbreaking position when a current of a predetermined value has traversed the same for a predetermined length of time, a thermal relay 58 is provided. As shown, the rela 58 is provided with a bracket 59 of substantially U-shape that is secured to the panel 10 by means of studs 61 and 62. To the upper portion of the bracket 59 that extends laterally from the panel, a magnet 63 of substantially horse-shoe shape is secured by means of a plate 64, that extends laterally across the face of the magnet, and a screw 65 that has screw-thread ergagement' with the bracket 59.

The bracket 59 and the plate 64 may preferably be of non-magnetic material and may be made, by a simple stamping operation, from a sheet of metal. To the lower horizontally extending portion of the bracket 59, a moveable contact-carrying member 66 is secured by means of a hinge pin 67.

The member 66 may be made by a simple stamping operation from a sheet of nonmagnetic material. As shown, the edges ofthe lower end of the member 66 are upturned, the upturned edges bein rovided with alined slots 68 with which a 1m 69 may have sliding engagement.

A contact-bridging member 71 is insulatedly secured to the member 66 by a clip 72 WhlCh may be attached to the member 66 by a rivet or an other suitable means. To the upper end 0 the member 66 an inductor or magnetic member 73 is secured by rivets or "other-suitable means, the inductor. compris- 5. ingu-pwardlyextending.members 7 4 and 7 5. w :As shown,-the--members 74 and 75 are .posintionedjadjacentrto the poles 77 and 78 of the 6 magnet.

When the contact-supporting member 66 "is in theposition shown in the drawings, the portions74 and 75 of the inductor 7 3 engage a reversibly magnetic member 79 that is elecvtrically gconnected to,:and supported by, a '..,'pair ofstuds 81 and 82 preferably of nonimagnetic-materials As shown, the studs are vprovided with screw-threaded end portions which pass through the base or panel 10, the end.:porti.ons being provided with nuts 83 by means of which the studs may be held securely on thebase.

1 The member 7 9.may be made of a nickelsteel alloyv containing approximately 35% iron,- 65'%- nickel with minor. percentages of otherzelements, as-desired. The characteristie of. this .alloy is such that, when heated to wa=temperature otapproximately 0., it becomes non-magnetic and, when cooled to a temperature slightly below this temperature,

:it, again becomes magnetic. For this reason, the member 79may betermed a reversibly 'magneticmember; that is, when normally cool,it'is magnetic;.when heated to a preat determi'ned temperature, it becomes nonmagnetic andzif permitted to cool below this temperature, it again becomes magnetic.

: Thenthe inductor 73v engages the reversibly magneticmember 79, a magnetic path ie. established fromthe pole 77, through the inductor 74, the member 79 and the inductor 75, tothehpole 78. However, if the member 79 becomes non-magnetic, the magnetic path *isbroken and'the member 66 is caused to swing outwardly, thereby actuating the in- 1 ductor 73 away from the poles of the magnet.

A-tthe same time, the contact-bridging memberis-also-movedoutwardly from the position shown in Fig. 1 of the drawing.

In order-that the circuit of themagnet coil 39 shall hes-broken, when the contactbridging-member .71 has moved outwardly upon release oft-he inductor 73 from the member 79, a pair of resilient contact memte bers 85 and 86 are provided. These contacts -may be yieldingly' supported at the ends of "p-the studs 61 and 62 by means of bolts 87 and springs 88, it being understood that the studs 61 and 62 are in circuit with the mag- 535 1161310 coil 39.

In order that the contact-bridging member 71 may be actuated into engagement with .:the resilient contacts 85 and 86 the moment e; the armature 18 is actuated to a position in ca which the vcontacttips 12 and 25 are disengaged,apush rod 89 is provided. As shown, the push rod moves vertically through apertures 91 and 92in the horizontally extending portions of. thebracket 59." The link 69 is pivotally secured to thepush rod 89. and is adapted to be. moved-vertically thereby. The push rod 89. may beactuated upwardly by a spring 93. that is located between the'lower horizontally extending portion of, the

bracket 59 and a stopsmember 94 attached to a .causing the link (39 to engage the member 68 and to actuate it to the position shown in Fig. 1. The portions 7% and 7 5 of the inductor 73 are, therefore, caused to engage the reversibly magnetic member 79 and the contact-bridging member 71 to re-engage the stationary contacts and 86.

It the armature 18 is in the position shown in Fig. 1 and the member 79 is heated to the temperature at which it is rendered nonmagnetic, the member 66 will be actuated downwardly by gravity to eifect the de-energization oi the magnet coil 39 and a consequent opening of the switch contacts 12 and Therefore, it is seen that the main circuit interrupter cannot be maintained in a circuit-making position until the member 79 has cooled to a ten'iperature at which it becomes magnetic.

It is to be understood that the member 79 may be made in various sizes and shapes, depending upon the thermal characteristics desired. T hat is, if the relay is to operate to tie-energize the coil 39 when a relatively small cu-rent traverses the main circuit interrupter, the thermal capacity of the member 79 should be relatively small and the resistance relatively high. If the relay is to operate at a higher value of current, the thermal capacity of the member 79 may be made greater and the resistance less.

In Fig. at ofthe drawings, an application of the device illustrated in Figs. 1 to 3 inclusive, is illustrated. As there shown, a motor 97 having a shunt field winding 98 is connected for enerqization between supply conductors 99 and 101. The motor may be energized by pushing a starting switch 102to the position illustrated by tne broken .lines, thereby effecting energization of the magnet coil. 39, the energizing circuit being from supply conductor 99 to the starting switch 102 a stepping switch 103 and the bridging contact member 71 to the supply conductor 101. When the coil 39 is energized, thecon tact tip 25 engages the contact tip 12, 5

shown by the broken lines, and the motor is then connected to the supply conductors 99 and Y101.

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As shown, the magnetically reversible member 79 is connected in series with the motor 97. When the main circuit interrupter has been closed by the magnet coil 39, the contact bridging member 54 engages the stationary contacts 55, thus establishin a per manent energizing circuit through'tfie magnet coil 39. The starting switch .102 may now be released to its full-line position.

If a current of a predetermined value has traversed the motor for a predetermined length of time, the member 79 will be heated to such temperature that it will no longer be magnetic. When such condition occurs, the contact-bridging member 71 is released to the broken-line position shown in Fig. 4, and the energizin circuit of the magnet coil 39 is broken, there y efi'ecting disengagement of the contact members 12 and 25 and deenergization of the motor.

The moment the motor is de-energized by the opening of the contact members 12 and 25, the spring 93 becomes effective to actuate the contact-bridging member 71 and the inductor 7 3 to the positions shown in Figs. 1 and 2. Thus, if the energizing circuit of the coil 39 is again established before the member 79 becomes magnetic, the contactbridging member will be released to its circuit breaking position to again eflect deenergization of the coil 39.

By my invention, I have provided a magnetic thermal rela for controlling the oper-v ation of a main circuit interrupter whereby the temperature of a motor or other electrical-energy-translating device may be limited to a safe value.

I have provided also, a relay that is automatically reset to its operative position Whenever the circuit interrupter controlled therebyhas been actuated to a circuit breaking position. However, the automatic resetting device is so constructed that the relay is permitted to drop out or to open a circuit when the thermal condition of the relay is above a predetermined value.

Various modifications may be made in the device embodied in my invention without departing from the spirit and scope thereof. I

. desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

1. A thermal relay comprising a support, a magnet carried thereby, a reversibly magnetic member, a movable member carried by said support, and an inductor carried by the movable member, said inductor being magnetically secured to said reversibly magnetic member by the magnetizing efi'ect of said magnet.

2. A magnetic thermal relay comprising a support, a permanent magnet carried thereby, a movable member, a reversiblymagnetic member an inductor carried by said movable mea y." l.

member for providing a magnetic circuit through the reversibly magnetic member and the m et, and means for effecting movement 0 said movable memberin nee to a change in the magnetic properties 0 said reversibly magnetic member.

3. A tic thermal rela comprisin a magnetical y reversiblev mem r, a move. le member, an inductor carried thereby for normally engaging said magnetically reversible member, and means for establishing a magnetic circuit through said inductor and reversibly magnetic member when in engagement.

4. The combination with a main circuit interrupter and a magnet coil for actuating said interrupter to a circuit-making sition upon the energization of said coil, 0 a thermostatic device for controlling the energizetion of said magnet coil, said device comprising a magnetically reversible member, means for heating said member in accordance with the current traversingbthe circuit interrupter, a movable magnetiza le member for engaging said magnetically reversible member when normally cool and for releasing the same when heated to a predetermined temperature, a permanent magnet for magnetizing said magnetizable member, and a circuit interrupter actuable by said magnetizable member for de-energizing-said magnet 0011 upon the occurrence of said temperature 5. The combination with a main circuit 1nterrupter for controlling a translating device, and a thermal relay for controlling the main interrupter, of a lost-motion mechanism for biasing said relay to one circuitcontrolling position only when the mam 1nterrupter is in a predetermined circuit-controlling position.

6. In combination, a magnetically reversi ble member, a movable member, an inductor carried by the movable member, a permanent magnet for magnetizi said inductor when the inductor engages t e magnet cally reversible member, means for heating said reversible member to a temperature of a predetermined value and means for efiect movement of said movable member when sai temperature is reached.

7. In combination, a main switch hav ng movable contact mechanism for controll ng a translating device, a thermally-responsive switch having movable contact mechanism, spring-actuated means for holding said thermally responsive switch in one position when the main switch is in an open position,

and means actuable by said main switch for 8. The combination with a main circuit interrupter for controlling a translating device and a thermal relay for controlling the main interrupter, of a resilient means having a lost motion connection With the relay for biasing it to a predetermined circuit-controlling position When the main interrupter is in a predetermined circuit controlling position.

In testimony whereof, I have hereunto subscribed my name this 16th day of June, 1927.

' EDWARD M. CLAYTOR. 

